The following description does not admit or imply that the apparatus or method discussed below is citable as prior art or part of the general knowledge of a person skilled in the art in any particular country.
In order to filter or permeate with hollow fibre membranes, a large number of thin hollow fibres must be fixed to a header such that their outer surfaces are each completely sealed to the outside of the header but their lumens are open to an inner space in the header. The inner space of the header is then connected to a source of suction or pressure to create a transmembrane pressure across the walls of the membranes and carry fluids to or from the lumens of the membranes.
In U.S. Pat. No. 5,639,373, the ends of an array of fibres are submerged in a fugitive liquid, such as a wax, until the fugitive liquid solidifies around them. A fixing liquid, such as a resin, is then poured over the fugitive liquid and allowed to harden around the membranes. The fugitive liquid is then removed, for example by heating or by dissolution, leaving the lumens of the membranes open to the space formerly occupied by the fugitive liquid. In U.S. Pat. No. 6,042,677, a similar process is used but the array of fibres is held in a bed of powder which is used in place of the solidified fugitive liquid.
In U.S. Pat. No. 5,922,201, a continuous hollow fibre is made into a fabric such that adjacent lengths of the fibres are spaced apart from each other and do not have open ends. An edge of the fabric is inserted into a pot of liquid resin which is centrifuged or vibrated as it cures to encourage flow into the spaces between the fibres. After the resin is cured, the block of resin and fibre is cut to separate the fabric into individual lengths of fibres having open ends. The block of resin is then glued or attached through gaskets to the remainder of a header.
In European Patent Application No. EP 0 931 582, an elastic pipe is used to make a header. An aperture is cut in the pipe and a weir is built up around the aperture. Open ends of hollow fibre membranes are inserted into the aperture by first pulling the aperture open and then allowing it to close on the membranes. Liquid resin is poured over the ends of the membranes and retained in placed by the weir until it cures. Surface tension prevents the resin from flowing through the aperture in spaces between adjacent fibres.